Heart valve regurgitation, or leakage from the outflow to the inflow side of a heart valve, is a condition that occurs when a heart valve fails to close properly. Regurgitation through the mitral valve is typically caused by changes in the geometric configurations of the left ventricle, papillary muscles and mitral annulus. Similarly, regurgitation through the tricuspid valve is typically caused by changes in the geometric configurations of the right ventricle, papillary muscles and tricuspid annulus. These geometric alterations result in incomplete coaptation of the valve leaflets during systole.
A variety of heart valve repair procedures have been proposed over the years for treating defective heart valves. With the use of current surgical techniques, it has been found that between 40% and 60% of regurgitant heart valves can be repaired, depending on the surgeon's experience and the anatomic conditions present. The advantages of heart valve repair over heart valve replacement are well documented. These advantages include better preservation of cardiac function and reduced risk of anticoagulant-related hemorrhage, thromboembolism and endocarditis.
In recent years, several new minimally invasive techniques have been introduced for repairing defective heart valves wherein surgery and cardiopulmonary by-pass are not required. Some of these techniques involve introducing an implant into the coronary sinus for remodeling the mitral annulus. The coronary sinus is a blood vessel that extends around a portion of the heart through the atrioventricular groove in close proximity to the posterior, lateral and medial aspects of the mitral annulus. Because of its position, the coronary sinus provides an ideal conduit for receiving an implant (i.e., endovascular device) configured to act on the mitral annulus.
As a result of the development of implants configured for insertion into the coronary sinus for repairing mitral valves, new systems and methods for delivering these implants have also been developed. For example, U.S. Pat. No. 6,210,432 to Solem et al., the entire disclosure of which is incorporated herein by reference, describes a stabilizing instrument onto which an implant may be mounted using a locking device including a pair of spring blades and knobs. After the implant is placed in a desired location in a patient, a catheter may be used to release the implant from the stabilizing instrument. In another example, U.S. Pat. No. 6,402,781 to Langberg et al. describes a deployment system including an introducer sheath and a pusher mechanism. The implant is contained within the introducer sheath during advancement into the coronary sinus. After reaching the desired location, the pusher mechanism is used to hold the implant in a fixed position while the introducer sheath is retracted. Yet another example of a delivery system is disclosed in Applicant's co-pending application Ser. No. 11/238,853, filed Sep. 28, 2005. This delivery system is configured to deliver and deploy a medical implant in a very predictable and secure manner. The delivery system is also configured for easy pre-procedure and peri-procedure flushing of all of the delivery lumens as well as adequate purging of air bubbles trapped in the catheter system to minimize the potential for air embolization during use of the delivery system.
Although a variety of implants and delivery systems have been proposed for treating mitral valve regurgitation in a minimally invasive manner, it has been found that existing implant configurations may lack the structural integrity necessary to effect a change to the mitral annulus located adjacent the coronary sinus. Accordingly, a need exists for an improved implant sized to be anchored at least partially within a coronary sinus and having sufficient strength to apply a compressive force along the mitral annulus for treating mitral valve regurgitation. It is desirable that such an implant be configured to evenly distribute forces to minimize stress concentrations and thereby reduce the possibility of fracture. It is also desirable that such an implant include anchoring portions which are capable of securely engaging an interior wall of the coronary sinus and/or coronary ostium or right atrium while being compressible for delivery to the treatment site. It is also desirable that such an implant be configured for percutaneous delivery and be relatively easy to manufacture. The present invention addresses these needs.